Grass sickness

Cottrell DF, McGorum BC, Pearson GT (1999) The neurology and enterology of equine grass sickness A review of basic mechanisms. Neurogastroenterol Modi 11 79—92. 

Hjqiochloremia is common in gastrointestinal disease (Svendsen et al 1979), because of the loss of gastric hydrochloric acid in high volume reflux from the stomach (in proximal enteritis and grass sickness) and the secretion and/or lack of absorption of chloride in severe colitis. It may also occur in exhausted horse syndrome, chronic compensated respiratory acidosis and following furosemide (frusemide) administration. Hypochloremia in the absence of hyponatremia results in a metabolic alkalosis (Corley Marr 1998). The alkalosis associated with hypochloremia may also result in increased cellular uptake of potassium, leading to hypokalemia (Schaer 1999). 

Nutritional disorders associated with grass pastures include nitrate poisoning, various mycotoxicoses and (in horses) grass sickness. 

As well as being inimical to preservation, Clostridia may be a health hazard to animals on diets based on contaminated silage. A number of cases of botulism, caused by Clostridium botulinum, have been reported in horses and cattle receiving such diets. The condition is uncommon in the UK but is more common in the USA and the Baltic countries. It has been claimed to be the causative organism of grass sickness of horses, although a nutritional trigger has also been postulated. 

Saccharolytic Clostridia break lactic acid down to acetic and butyric acids, causing a rise in pH and putting preservation at risk. Proteolytic Clostridia break down amino acids with the production of a number of unpleasant substances. Clostridium botulinum is the causative organism of botulism and has been associated with grass sickness in horses. 

This has been referred to as soil sickness, or a sod-bound condition for grasses. Often, the cause is unknown, but the problem for several legumes may be due to allelopathy. In soil sickness of red clover pfiatzyiiz L.), isoflavonoid and phenolic acid... 

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